Somewhere in the CBC/SRC DTV Transition Status (closed)
thread, there was mention that CBC's analog distribution network is coming to the end of its useful life in 2013.
In the July 2011 CBC proposal, the CRTC approved the CBC to continue analogue transmission in the 22 'mandatory' markets. I also remember reading that the CRTC directed the CBC to report back in June 2012. I guess we'll find out whether the CBC changed their digital conversion plans for the mandatory markets next June. (I hope so!)
If London and other 'mandatory' markets have their CBC transmitters shutdown, there will be huge CBC ota broadcasting voids all over Canada, in areas with large populations.